


cynosure

by oryx



Category: Kamen Rider Den-O, Kamen Rider Fourze
Genre: Crossover, Fluff and Humor, Gen, the universe's #1 teacher gen-chan
Language: English
Status: Completed
Published: 2019-05-08
Updated: 2019-05-08
Packaged: 2020-02-28 06:41:53
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,319
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18751081
Author URL: https://archiveofourown.org/users/oryx/pseuds/oryx
Summary: Gentaro consults the experts in regards to some time travel issues.





	cynosure

**Author's Note:**

> for alexandria <3 thank you so much! i may have gone a little more sappy than intended, as i am wont to do. hope it's not too embarrassing.

  
The Denliner makes a sudden swerve. Everyone’s coffees go sliding off the table with an awful  _smash_ , dark liquid and disgusting coloured foam covering the floor like a very comical crime scene.  
   
“Hey, what – ”  
   
It swerves again. Ryuta almost goes tumbling out of his seat, caught by the scruff of his neck at the last moment by Kin.  
   
“What’s with this?” Momo demands, calling over to where Naomi is staring mournfully at the remnants of the parfait she’d been painstakingly putting together. She sighs, shoulders slumping low.  
   
“Um. I think we’re being flagged down. But like. By someone who doesn’t know what they’re doing?”  
   
“Haa?” Momo clambers over the turtle bastard to press his face against the window, observing the moment the train leaves the Sands and enters the stable reality of the human realm, appearing high above what looks to be a school. As it arcs lower he can make out a solitary figure down below, seemingly waving a pass around like an utter dunce.  
   
Grumbling to himself, Momo makes his way out to the doors to be there when they slide open.  
   
“Hey, you!” He leans out, jabbing a finger in the human’s direction. “What the hell d’you think you’re doing? There’s – there’s  _protocols_ for that thing, y’know!” He takes a second to feel a bit proud for coming up with a fancy word like ‘protocols.’  
   
The guy – grey suit, bright red sneakers, artfully slicked back hair and an affable face – stares up at him and the train with wide eyes. “Whoa, it really worked,” he says with a laugh. He grins, then, stepping forward and hopping up through the doors, forcing Momo to move back to accommodate him. Up close, he seems to exude some weird aura of pure enthusiasm, and Momo promptly backs away some more.  
   
“Not like I doubted him,” the human is saying, peering around at the interior. “But it’s all just kinda wild to think about, right? Time trains popping out of the sky.” He hums to himself as he wanders into the dining car, tapping the pass against his shoulder. Something about it catches Momo’s eye. The initials written on it. ‘R.N.’ The slight scorch mark on the corner of the case, the result of some Shenanigans that were definitely Not Momo’s Fault.  
   
He’s moving to block the human’s path in an instant, grabbing him by the collar and twisting his fingers into the fabric.  
   
“That’s Ryotaro’s pass,” he growls. “Where’d you get it?”  
   
Behind him, he can feel the others sit up and pay attention, a wave of apprehension cutting like a knife through the room.  
   
“Oh, he lent it to me,” the human says brightly, seeming not to notice the mood. “He’s a good dude, isn’t he?” A thought apparently occurs to him, and he starts to pat down his pockets one by one, until finally he reaches into his jacket and finds what he’s looking for, pulling out a slightly crumpled note that he hands to Momo with a smile. “He wanted me to give this to you.”  
   
Momo hesitates, uncertain. Slowly, he releases his grip on the guy’s collar and accepts the note, and the other three crowd around behind him to read over his shoulder as he unfolds it.  
   
_Hey everyone!_  
   
_Momotaros, please put down the sword or the fist or whatever you’re threatening Kisaragi-kun with right now. I swear up and down that I really did loan him my pass. I met him through some strange circumstances… Though I guess no weirder than the usual._  (A small illustration of a face with a cartoon sweatdrop is drawn next to the words.)  _He’s having “time troubles,” so to speak. I knew right away that you all could probably help him better than I could. Be nice, okay? Or at least respectful. He’s a Kamen Rider, too. And Riders should help each other out, remember?_  
   
_I miss you guys. – Ryotaro_  
   
There is silence, and then the bear laughs, deep and resonating, a fond sort of sound that breaks down whatever quiet tension still remained. “Well, this is just like him, isn’t it?”  
   
“Indeed,” Ura says, a smile in his own voice. “Who else would just give these things away to anyone who needs it?”  
   
“You’re really a Rider?” Ryuta says, leaning in closer to stare up at their guest, who thumps a fist against his chest proudly.  
   
“Sure am. Kamen Rider Fourze, Kisaragi Gentaro. The man who’s gonna befriend every other Rider. So I guess that means you guys, too!”  
   
“Befriend?” Momo echoes, putting what he hopes is sufficient disdain into the word. He adds a ‘tch’ for dramatic effect. “Aren’t you gettin’ ahead of yourself, chump? You might be okay in Ryotaro’s eyes but that’s not ever gonna make us  _pals_. Got it?”  
   
“But what if I did… this?” Gentaro says, his grin somewhat sly, and promptly reaches out to initiate the most incredible secret handshake that Momo has ever seen or experienced. “Now we’re absolutely buds, and there’s no taking it back, sorry!”  
   
Momo stares down at his hand, stunned and awestruck in the aftermath.  
   
“Oi, did… did you see that?” he hisses to Ura. “That was – he was so damn cool about it! What the hell!”  
   
“Mmhmm. By your standards it was definitely very ‘cool,’ senpai,” he replies drily. He seems to be observing Gentaro in that calculating, contemplative way of his, watching him as he happily performs the handshake with Ryuta as well, who’s literally bouncing up and down with excitement and making it a bit difficult.  
   
“What did Ryotaro mean by ‘time troubles,’ exactly?” the turtle asks.  
   
“Hm? Oh, well.” Gentaro pauses, rubbing at the back of his neck thoughtfully. “Not really sure about it myself. Three weeks ago I was just walking back from the staff room, right? And then I turned the corner and I was just. In a different time. I think? Like I’m sure it was morning, suddenly, even though it’d just been five pm. I was the only one in the school, it seemed. And when I saw a calendar on the wall, it said it was April 2016. Like I’d gone back three whole years somehow.” He frowns. “It was pretty weird, to be honest. But then I stepped through a door and I was just back in the present again, and everything seemed okay. So I figured it was nothing to worry about too much.”  
   
“You’re a pretty easygoing guy, huh?” Naomi says, raising an eyebrow. She has her chin resting on her palm as she listens to his story from behind the counter.  
   
Gentaro laughs, cheeks dimpling. “Y’think so? ‘S better not to get hung up on stuff, I’ve always thought.” He hesitates before continuing: “But when it happened again I was kinda. Starting to get a little confused, y’know? This was a few days after the first one. The calendar said August 2016 that time. And then the third time, when I was out jogging, I was crossing this bridge and the whole thing just vanished out from under me! I think maybe ‘cause it didn’t exist yet three years ago? Anyways, that’s when I met Ryotaro. I kind of. Landed on him, actually?”  
   
A quiet murmur of sudden understanding travels through the car.  
   
“Yeah, that sounds about right,” Momo says.  
   
He can’t help but feel a bit fond and wistful, thinking of Ryotaro out there getting besieged by random folks falling from the sky. Probably laughing it off in that sheepish way of his and saying “oh no, this kind of thing happens all the time.” Classic Nogami family nonsense.  
   
“Sooo,” Ryuta says, tapping a claw against his chin. “You’re like all… floaty? In time?”  
   
“If it was that simple, he wouldn’t keep ending up in the same year,” Ura says. “There must be something about 2016. And some force that’s dragging him back into it.”  
   
Gentaro folds his arms over his chest. “2016, huh?” His face scrunches up as he seems to wrack his brain. “I don’t remember any big stuff happening then, to be honest. Had a good class of kids that year. But I have a good class every year!”  
   
“Hm. So then it might be someone else’s memory affecting you, somehow? I wonder if maybe – ”  
   
Momo makes a frustrated noise. “Ahh, who cares about all this! Let’s just go… I dunno! Do something about it!”  
   
“A comprehensive plan of action, as always, senpai.”  
   
Gentaro’s eyes light up, reaching out to clap Momo on the bicep in an overwhelmingly friendly manner. “You’ll really help me out?”  
   
“Well, that’s – ” He clears his throat. “‘Course we will. Since Ryotaro said to. And you seem like a pretty stand-up guy.” Instilling his voice with more confidence, he continues: “You remind me of myself, y’know. A man who’s not afraid to be bold.”  
   
Gentaro’s grin broadens, and Momo pretends not to see Naomi rolling her eyes in the background.  
   
  
   
  
   
The old pass comes in handy for the second time that day, as Owner’s eerie voice over the intercom informs him that with concentration and a powerful enough memory it can grant him the appearance of a human, at least for a little while. Which is how he finds himself standing at the gates of Amanogawa High School looking, for the first time in a long time, like Ryotaro.  
   
It’s an odd feeling. As Gentaro leads him across the school grounds he stops to stare at his own reflection in one of the windows. Runs a hand through his spiked hair and tilts his head to the side. Some part of him had wondered if he’d ever see himself like this again.  
   
“It’s so cool,” Gentaro is saying. “That you guys fought together with him like that. Wonder what it’d be like to get possessed… Maybe I’m kinda glad it was just me in my head being Fourze, but. Having all your buds in there might be fun, too.”  
   
“Four, five Imagin is way too damn many,” Momo mutters. “Dunno how Ryotaro put up with all of us. Patience of a saint, that guy.”  
   
Gentaro laughs as he leads him around the corner of one building. School is apparently out at this late afternoon hour, the light turning orange and shadows beginning to slant across the ground, but there are still students milling around campus, taking part in those ‘clubs’ that he’s heard humans talk about. On the soccer field in the distance, two girls stop their goal-shooting and wave to Gentaro.  
   
“Hey, Kisaragi-sensei,” they call. “Who’s your friend?”  
   
“I’ll tell you tomorrow,” he yells back, hands cupped around his mouth. “You better practice hard, okay?”  
   
“O~kay,” is their singsong reply.  
   
Gentaro comes to halt on the covered connecting path between the two buildings. “This is about where the second, uh. Time hop happened.” He turns to Momo with wide eyes. “D’you, like. Feel anything? With your time powers?”  
   
Momo stares back at him blankly. “Time powers?”  
   
“Yeah, y’know. ‘Cause you’re a magic time guy and all that. So you’ve gotta have some sixth sense for it, right?”  
   
Oh, hell. Time sense? Is he supposed to have that? Do other Imagin have it? None of those other fools ever mentioned anything about it, but it would be just like them, keeping him in the dark about important stuff for more than a decade. Laughing about it behind his back, probably.  
   
“Right,” he says loudly. “ _Those_  time powers. Uh. Just. Hold on a sec.” He screws his eyes shut, pressing his fingertips to his temples, and tries to do some sort of timey thing.  
   
Seconds tick past.  
   
When he opens his eyes, Gentaro is still smiling at him expectantly, and Momo shifts his weight from foot to foot, awkward under the scrutiny.  
   
“Okay, well. You gotta understand that the, um. Time energies have to be in the right coordinates for these things to… to… ”  
   
He trails off. Gentaro’s expression has changed, his mouth in the shape of an ‘o.’ He’s staring at something just past Momo’s shoulder, and Momo turns to see an inexplicable distortion happening to the air behind him – as if reality were two halves of a photograph that’s been sliced neatly in half and put back together slightly off-center. A gap seems to widen between the halves, a strange space in the world that blends in with the surroundings but also not quite, and inside it he can see –  
   
Something moving. Something monstrous. Twisted and gnarled-looking, with glowing green eyes.  
   
As quickly as it had appeared, the space snaps closed and the distortion corrects itself, the world sliding back into place, leaving nothing at all to show that it had been there.  
   
“Huh,” Gentaro says. “Well that was weird.”  
   
  
   
  
   
He seems oddly energized when he jogs up to meet him again, a chunky device accessorized with several colourful switches tucked under his arm. The Fourze Driver, is what he’d said he was heading in to get. Privately, Momo thinks that the Den-o belt is much cooler.  
   
“I always keep it in the drawer in my desk,” Gentaro explains. “Never know when some stuff might go down, right?” He pushes back a strand of hair that’s fallen out of his pompadour with a slightly guilty grin. “But it’s been a while since I had anything to fight, honestly. Which is good! But like. Y’know. Sometimes you get a little restless. Start itching for something to happen.”  
   
Momo blinks. “You… You feel that way, too?” Pressing a hand to his mouth, overcome with sudden emotion, he reaches out to punch Gentaro affectionately in the shoulder. “You really get it, man. Nothing better than a good brawl once in a while.” His throat feels a bit thick. Never thought he’d meet a Rider kouhai who  _understood_. “C’mon, let’s go find whatever the hell that thing was and beat it up.”  
   
The purplish evening is fully upon them by the time they make it to the bridge that Gentaro claims vanished right out from under him. It’s empty at this hour, and the rest of the city feels far away from here, the sounds of traffic distant.  
   
“Guess if that thing is gonna show up again it’d probably be here,” Gentaro says, and nods to himself very seriously. Momo isn’t entirely sure what logic they’re basing this on, but he’s never been one to ask too many questions. “And maybe by being here we can keep it away from the school. Since it only seems to be after me, for whatever reason.” He frowns at that. “The idea of a fight is pretty exciting, but. It hasn’t really attacked me yet, has it? Wonder if that’s what it’s really after.”  
   
“Maybe it wants to use your Fourze power for somethin’?” Momo suggests.  
   
Gentaro visibly brightens. “You mean it wants to be friends?”  
   
“Uh. Nah, that’s not really what I – ”  
   
He’s the one who notices it first, this time. The distortion. The shadowed space underneath the bridge seeming to slice itself in half and slide apart.  
   
And this time, the monster inside staggers out.  
   
His earlier thought, that it looked ‘gnarled,’ turns out to be surprisingly on-the-nose – it resembles a tree, he thinks, its body seeming to have the texture of bark, with flowering branches of pink blossoms twisting out from its shoulders. Momo peers closer and sees something etched in the bark around its green eyes. Numerals? Like the numbers on the face of a clock. It opens its mouth and a strange, groaning voice emerges.  
   
“Sen…” it says, lifting a hand in their direction. “Sens…”  
   
“Eh? What’s it saying?”  
   
“Dunno.” Gentaro takes a step closer, tentative, and that is when the thing shudders, seemingly caught in place, its edges shifting like static on an old tv screen before solidifying again into this plane of reality.  
   
Its eyes gone jet black, it lunges for him with a swipe of its claws.  
   
They both jump back in unison.  
   
“Never mind, then,” Gentaro says, his smile rueful but his eyes bright. “Guess there’s no talking it out, huh?”  
   
Momo can feel himself grin, too, as he materializes the Den-o belt in his hand and snaps it into place around his waist. “Guess not,” he says, and the announcement of ‘Sword Form’ overlaps with the countdown from Gentaro next to him.  
   
  
   
  
   
The fact of the matter is that they’re both old hand at this. He can see it in the way Gentaro fights that he, too, has again and again dealt with threats far more severe than this – has seen him in action before, now that he thinks about it, those rare times that the Riders have all found themselves thrown together into bizarre world-encompassing conflicts.  
   
It doesn’t take much to win this particular fight. Momo watches, whistling appreciatively at the execution, as Fourze’s Rider Kick connects squarely with the creature’s chest, sending it careening back into the stone wall behind it with a  _slam_  that raises a cloud of debris.  
   
“Nice one,” he calls, jogging up with his sword against his shoulder, eyeing the figure within the settling dust to see if they’re well and truly down for the count.  
   
When it disperses, there is a human slumped against the wall.  
   
“Wait,” he says, leaning in to get a better look as he frowns behind the helmet. “What?”  
   
“So it was a person,” Gentaro murmurs. He lets the Fourze armor fade away in a rush of light, and Momo hurries to follow suit. Gentaro crouches down next to them, hand on their shoulder, tipping them back in order to reveal their face, and –  
   
“I know her,” he says softly.  
   
“Wh – seriously?”  
   
She’s a young woman, maybe about twenty, with sharp, thin features and hair cut in a short bob. She looks tired. Even while unconscious it’s evident, the kind of tiredness that writes itself into the planes of someone’s face.  
   
“She was one of my students,” Gentaro says. “A few years ago. ...In 2016.”  
   
He pats her cheek lightly, shaking her a bit by the arm, and this seems to rouse her, little by little, her eyes fluttering open partway to peer at them blearily. When she realizes who she’s looking at, she jolts into total wakefulness with a start.  
   
“Sen…sei?”  
   
Gentaro grins back at her. “Hey, Enoshima. Been a while.”  
   
Startled disbelief flickers across her face. “You… You remember me?”  
   
“‘Course I do. I remember every kid in my classes. Enoshima Kasumi, 2-A. In the art club. Right? You sat by the window.”  
   
She swallows visibly. “Yeah,” she says. “Yeah, I. I wasn’t really the best student to you, though. I was always just… in my own head. Never really there. I didn’t manage to apologize for that before I graduated. So, um.” She ducks her head. “Sorry.”  
   
Taken aback, Gentaro tries to wave her apology aside. “Oh, man,” he laughs. “It’s okay, really! I could always tell you had a lot of ideas and creativity and stuff. And you got way into it. Shouldn’t say sorry for that. To be honest, I liked seeing whatever you were doodling whenever I walked by your desk.”  
   
Enoshima looks, in this moment, as if she might cry.  
   
“You were the only one, sensei,” she says, and her voice comes out a bit hoarse. “Who ever looked so impressed by one of my drawings. And told me I could make it a career. No else has ever… believed in me like that.” She smiles, wry and bitter. “I guess what I should really be apologizing for is… All of this. The time stuff. And attacking you like that, I didn’t mean to, I swear I don’t know what happened – ”  
   
“Oi,” Momo says, feeling for this girl but getting the distinct impression that she’s about to start freaking out. “How’d this start, exactly?”  
   
She stares up at him for a moment, like she’s only now truly noticed his presence. “Um. Right. It… was this.” She lifts the chain around her neck, pulling it over her head and revealing something hanging from it – an ornate golden pocketwatch. When she flips it open, the numerals around its edge are strangely hard to make out, as if they were flickering in quick succession from number to number.  
   
“Someone gave this to me,” she explains. “I didn’t know him. He just… appeared out of nowhere and said I could use it. To go back to when I was happier. And he said there’d be a catch, that time would go weird and I might change but I didn’t care, I – ” She presses her lips together in a thin line and shakes her head. “I just wanted to experience it again so badly. Having you cheer me on. I didn’t appreciate it enough before.”  
   
Gentaro hums, thoughtful, sitting back on his heels. He runs a thumb over the engravings on the pocketwatch; wordlessly hands it to Momo for him to examine in turn. (There’s an odd weight to it for such a tiny thing, he thinks. Like it’s trying to sink down beneath the skin of his palm.)  
   
“Y’know you don’t have to go back in time for that, right?” Gentaro says.  
   
Enoshima’s gaze snaps up to blink at him.  
   
“I mean. My door’s always open,” he continues with an easy smile. “Love to see folks who’ve graduated come back to visit. I’ll root for you any day, whenever you want me to. And even if you’re too busy to come see me, I’ll still be rooting for you.”  
   
He points at the sky, and all three of them tilt their heads back to observe the night that’s fallen over them. The moon is a thin crescent, almost obscured by the halo of glow surrounding it. A few tiny stars blink faintly against the hazy dark.  
   
“It’s tough to see, right?” Gentaro says. “‘Cause we’re here in the city, with all the lights. But it’s all still there. All the constellations, and the planets, and the whole huge universe. They’re turning up there.” A contented pause. “We can feel kind of alone sometimes. But that’s just ‘cause our eyes don’t always see so far, y’know? We’re not seeing all the things and people that’re out there, outside our field of vision.”  
   
Enoshima seems to be struggling to keep it together as she stares up at the sky. She sniffles, blinking hard, and for some reason Momo feels it, too, in this moment, a strange tightness wrapping itself around his chest. The corners of Ryotaro’s pass dig into his hand. If the sky was clearer, he wonders if he could make out the Big Dipper. That’s the only constellation he ever bothered to learn.  
   
“Thanks, sensei,” Enoshima says softly. She hesitates; adds: “Can I… come see you tomorrow? After your classes are out?”  
   
Gentaro grins, and nods, and reaches out for a handshake.  
   
  
  
   
  
   
“Honestly, you’re pretty wise for a human brat,” he says, arms folded thoughtfully over his chest as they walk the path back to Amanogawa.  
   
“Wise?” Gentaro echoes. He laughs, looking somewhat pleased and awkward in the glow of the overhead streetlamp. “I dunno about that. I just say whatever pops into my head, y’know? It’s not some big thing.”  
   
“Well it works on people. And that’s what matters most.” Momo stops; lifts the strange pocketwatch by its chain into the light and watches the unsettling way the engravings glint. “You don’t want this thing, do you? ‘Cause if not I’m gonna give it to someone I know who seems like he’s dealt with crappy cursed time artifacts before.” Owner will keep it safe, at least. Probably. The guy’s inscrutable, but good for something like this, he’s fairly sure.  
   
“Yeah man, you can take it. Not sure what use I’d have for it.”  
   
“And you don’t need Ryotaro’s pass anymore, right? ‘Cause I, uh…” He slips the watch back into his pocket and slides the pass free in its place, staring down at it. The familiar shape in his hand. A certain anticipatory warmth is prickling at the back of his neck. “For some reason I just feel like. I might see him again soon. And then I can give it back to him.”  
   
He can feel the weight of Gentaro’s smile even in the dark. “Definitely,” he says. “He deserves to have it back.”  
   
They walk the rest of the way to Amanogawa’s gates in companionable silence.  
   
Momo lets his human disguise fade away as the whoosh of displaced air tells him that the Denliner has arrived for him. “You’re a pretty alright guy, Kisaragi,” he says. He holds out his fist, and Gentaro bumps his knuckles against his with a laugh.  
   
“You too, Momo-chan.”  
   
He freezes in place. “ _Momo-cha_ … Hey!” He bares his fangs in a glower. “What the hell kinda name is that, pal? Actin’ all familiar after a day! Just ‘cause you’re a bit cool doesn’t mean y – ”  
   
“Oh my god, would you shut up?” A familiar tiny hand with an absurd amount of power behind it grabs him by the collar and begins to haul him back through the train’s open doors as he fruitlessly protests. Kohana glares up at him once he’s been manhandled inside. “We’re on a tight schedule here, idiot.”  
   
“Time traveling train runnin’ on a tight schedule don’t make any damn sense,” he mutters, but goes quieter still when her next glare is even more vicious.  
   
“Thank you for babysitting him,” she calls to Gentaro. “If you need anything else just shout and we’ll probably maybe hear it – since you’ve been onboard now that means you’re a valued patron!”  
   
“Hey, thanks to you, too!” Gentaro calls back, and keeps waving even as the doors slide shut between them and the train shudders into motion on its airborne track.  
   
Momo watches him until he’s only a speck down below. Hard to see against the growing dark. But still there.  
   
Maybe it’s really not so bad, he thinks. Helping other Riders out now and again.


End file.
